It has long been the appetency of the art to convert a black-and-white positive picture, such as an opaque print, a single frame of transparent film, or a motion picture film, to a color film having gradations of color values.
Many of the black-and-white motion pictures now in storage are considered almost obsolete in the current color-saturated era merely because they are black and white. This obsolescence is especially true in the television industry where there exists a nearly exclusive demand for colored programming of motion pictures and commercials. Stored motion picture films such as "Streetcar Named Desire"; "On the Waterfront"; and "Not as a Stranger" could be in demand today if they had been originally photographed in color or could be converted to a colored film. Likewise, many of the black-and white television commercials that received particularly high public acceptance could be rerun if they could be converted to a colored film.
One method of adding color to a black-and-white motion picture is disclosed by O'Brien in U.S. Pat. No. 2,127,829, wherein the black-and-white image from a single motion picture frame is projected through accurately cut and accurately positioned colored filters onto a translucent screen and this combined image is then photographed with color-sensitive film from the opposite side of the screen. Thus, for each object within a frame, and for each distinct color within each object, a separate color filter has to be accurately cut and accurately positioned in a jigsaw-puzzle manner on the translucent screen. Adjacent filters, of the same or of different colors, may not overlap because an overlapped combination would produce a new and distinct third color between the adjacent filters; nor may the adjacent filters be mismatched to leave a gap because the gap would produce a white line on the color-sensitive film. Also, the color filters fail to transmit, in proportion to the original intensities, a significant portion of the gray scale and thus much of the black-and-white detail is lost while passing through the color filters and the number of available filters does not approach the variety of colors desired to adequately color a motion picture. The substitution of transparent paint or ink for the filters of O'Brien has been attempted, thus increasing the number of available colors, without overcoming the problem of overlapping and intermixing of adjacent transparent paint which would result in a third and distinctly new color between the originally distinct colors.
Another method of utilizing a black-and-white motion picture film to produce a colored film has been developed for producing colored animated cartoons. The first animated cartoons were produced from pictures drawn by artists showing sequential positions of moving objects on separate sheets. The sheets were then photographed on consecutive frames of a motion picture film. With a desire to eliminate a major portion of the artist's work, scenes were enacted by the aid of living actors depicting the subjects to be displayed by the cartoon and their movements were photographically recorded on a motion picture film. The motion picture was then projected from underneath a working table onto the underside of a ground-glass surface. Upon the upperside of the ground-glass surface was placed a piece of tracing paper on which an animation artist traced a verge or outline around a component part of the projected image. In tracing the projected image, the skillful artist would generally exaggerate or modify particular elements or features of the actor in order to produce grotesque characteristics on the cartoon character. The tracing paper, after being suitably colored, was then removed from the ground-glass surface for subsequent sequential photographing on a color-sensitive film. The motion picture of the live actors was therefore utilized to lend life-like realism of proportion and movement to the cartoon character but it was essential that the projected image from the black-and-white motion picture film was not photographed in combination with the traced cartoon character for the projected scene would tend to destroy the comic effect of the cartoon character.
Still another method of producing animated colored cartoons is where the motion picture background image is photographed in combination with an opaque cartoon character positioned between the projected image and the camera. Thus, the opaque cartoon character is superimposed on the actual background image and this combination is subsequently photographed. For example, see Gilmartin, U.S. Pat. No. 1,715,230.
One method of adding color to an opaque black-and-white print is the portrait tinting process wherein a photographic retoucher, an artist, mixes and applies a large variety of opaque colors directly onto an enlarged opaque black-and-white print photograph. Here, the skillful artist mixes and selects paints to selectively or completely cover and color the black-and-white photograph. The gray scale of any area to be colored is not used to produce a gradation of color; rather, additional colors are added to shade and accent the photograph to make it more natural appearing.